Biochem - Metabolism (Fatty acid metabolism, Ketone bodies, & Metabolic fuel use) Flashcards
Pg. 115-116 in First Aid 2014 Sections include: -Fatty acid metabolism -Ketone bodies -Metabolic fuel use
What does long-chain fatty acid degradation require?
Long-chain fatty acid degradation requires carnithine-dependent transport into mitochondrial matrix; Think:”CARNitine = CARnage of fatty acids”
What is the major metabolic defect and effect in Carnitine deficiency?
Carnitine deficiency: inability to transport LCFAs into the mitochondria, resulting in toxic accumulation
What are 3 symptoms/signs of Carnitine deficiency?
Causes weakness, hypotonia, and hypoketotic hypoglycemia
What are 3 signs of Acetyl-CoA dehydrogenase deficiency?
High dicarboxylic acids, Low glucose and ketones
What role does acetyl-CoA play in gluconeogenesis? What results from low acetyl-CoA?
Acetyl-CoA is a positive allosteric regulator of pyruvate carboxylase in gluconeogenesis; Low acetyl-CoA => Low fasting glucose
What substance begins fatty acid synthesis?
Citrate; Think: “SYtrate = SYnthesis”
Draw the major steps leading to fatty acid synthesis. Include the locations of the cell in which these occur.
See p. 115 in First Aid 2014 for visual in middle left of page
Draw the major steps leading to fatty acid degradation. Include the locations of the cell in which these occur.
See p. 115 in First Aid 2014 for visual in middle right of page
What is used to shuttle fatty acids to synthesis versus degradation? In what direction is each shuttle?
FATTY ACID SYNTHESIS: Citrate shuttle out of mitochondrial matrix into cytoplasm; FATTY ACID DEGRADATION: Carnitine shuttle out of cytoplasm into mitochondrial matrix
Into what products does the liver metabolize fatty acids and amino acids, and why?
In the liver, fatty acids and amino acids are metabolized to acetoacetate and Beta-hydroxybutarate (to be used in muscle and brain)
What are the 3 major conditions that lead to the production of ketone bodies, and what mechanisms/processes does this occur in each case?
In (1) prolonged starvation and (2) diabetic ketoacidosis, oxaloacetate is depleted for gluconeogenesis. In (3) alcoholism, excess NADH shunts oxaloacetate to malate. Both processes cause a buildup of acetyl-CoA, which shunts glucose and FFA toward the production of ketone bodies
How many kcal is each of the following: (1) 1 g protein or carbohydrate (2) 1 g fat (3) 1 g alcohol?
(1) 1 g protein or carbohydrate = 4 k cal (2) 1 g fat = 9 k cal (3) 1 g alcohol = 7 kcal
Draw a graph of time (x - 2 sec, 10 sec, 1 min, & 2 hrs) versus % maximal energy by source, including the following graph lines: (1) Stored ATP (2) Creatine phosphate (3) Anaerobic metabolism (4) Aerobic metabolism (5) Overall performance.
See p. 116 in First Aid 2014 for visual at top of page.
What are the body’s priorities in fasting and starvation states?
Priorities are to supply sufficient glucose to the brain and RBCs and to preserve protein
What is considered to be the fed state? What fuel metabolism occurs in the fed state? What is the predominating mechanism?
Fed state (after a meal); Glycolysis and Aerobic respiration; Insulin stimulates storage of lipids, proteins, glycogen
What is considered to be the fasting state? What fuel metabolism occurs in the fed state, and which is most minor vs. major? What is the predominating mechanism?
Fasting (between meals); Hepatic glycogenolysis (major); Hepatic gluconeogenesis, Adipose release of FFA (minor); Glucagon, adrenaline stimulate use of fuel reserves
What are 4 processes that maintain blood glucose levels in days 1 to 3 of starvation?
Blood glucose levels maintained by: (1) Hepatic glycogenolysis (2) Adipose release of FFA (3) Muscle and liver, which shift fuel use from glucose to FFA (4) Hepatic gluconeogenesis from peripheral tissue lactate and alanine, and from adipose tissue glycerol and propionyl-CoA (from odd-chain FFA - the only triacylglycerol components that contribute to gluconeogenesis)
When do glycogen stores deplete in starvation?
Glycogen reserves depleted after day 1
What is important to know bout RBCs in the context of starvation?
RBCs lack mitochondria and so cannot use ketones
Graph weeks of starvation (x) versus stored energy in kg (y), indicating the decline in the following energy sources: (1) Carbohydrate (2) Fat (3) Protein.
See p. 116 in First Aid 2014 for visual near middle/bottom right of page
What is the main source of energy in starvation after day 3? What happens if this source is depleted?
Adipose stores (ketone bodies become the main source of energy for the brain). After these are depleted, vital protein degradation accelerates, leading to organ failure and death.
What determines survival time in starvation after day 3?
Amount of excess stores determines survival time
What is the main source of energy for the brain in starvation after day 3?
Adipose stores (ketone bodies become the main source of energy for the brain)
